I. Field
The present disclosure relates generally to circuits, and more specifically to amplifier.
II. Background
Amplifiers are commonly used in various electronics devices to provide signal amplification. Different types of amplifiers are available for different uses. For example, a wireless device such as a cellular phone may include a transmitter and a receiver for bi-directional communication. The transmitter may utilize a power amplifier (PA), the receiver may utilize a low noise amplifier (LNA), and the transmitter and receiver may utilize variable gain amplifiers (VGAs).
An LNA is commonly used in a receiver to amplify a low-amplitude signal received via a communication channel. The LNA is often the first active circuit encountered by the received signal and hence has a large impact on the performance of the receiver in several key areas. First, the LNA has a large influence on noise performance since the noise of the LNA is injected directly into the received signal and the noise of subsequent stages is effectively reduced by the gain of the LNA. Second, the LNA should be able to handle large interfering signals (or jammers) that may come from external and/or internal sources. These interfering signals may cause intermodulation distortion, which may fall within the desired signal bandwidth and degrade receiver performance.
There is therefore a need in the art for an amplifier with good noise performance and capable of handling large interfering signals.